Base frame for a self-erecting marine platform

ABSTRACT

A base frame for a self-erecting marine platform is used in a method for erecting the self-erecting marine platform, which includes initially rigidly anchoring the base frame to the sea floor. Bearing columns of the marine platform are then hydraulically extended, for example, until the columns come into contact with support regions for supporting the marine platform under water. The bearing columns are then rigidly connected to the base frame. The self-erecting marine platform can therefore be used in deeper sea water.

The invention relates to a base frame for a self-erecting marine platform and to a method for erecting a marine platform.

A self-erecting marine platform is known for example from EP 0 959 182 B1. In that instance, a self-erecting oil platform is described, which has a housing floating on the water or, in other words, a pontoon with a substantially rectangular outline that, in its corner regions, has supporting columns that can be extended downwards in a telescopic manner. The marine platform is produced in the graving dock and is towed floatingly by ships to its location of use once the graving dock has been flooded. The telescopic support columns are then extended downwards to the sea floor, where they are anchored rigidly. The support columns are extended until the marine platform lifts from the water and is held above the water surface at the necessary safety height. To increase the stability of the marine platform, the downwardly extendable feet are equipped at their lower end with reinforcements. A disadvantage of self-erecting marine platforms lies in the fact that the maximum sea depth up to which these platforms can still be erected is currently limited to 45 m.

The object of the invention is therefore to provide a possibility with which self-erecting marine platforms can also be used in deeper seas.

The invention achieves this object by a base frame for a self-erecting marine platform, wherein the base frame has anchor means for anchoring the base frame to the seabed and a foundation framework, which is connected rigidly to the anchor means, wherein the foundation framework has support regions for supporting the marine platform.

The invention further achieves this object by a method for erecting a marine platform, in which a base frame is anchored rigidly to the sea floor beneath the sea surface, a self-erecting marine platform is supported on the base frame, and the base frame is then connected rigidly to the self-erecting marine platform.

In accordance with the invention, the self-erecting marine platform is no longer anchored directly to the sea floor by means of its extendable support feet, as is the case in the prior art. Rather, a base frame is used, which is anchored rigidly to the sea floor by its anchor means. The self-erecting marine platform is then fitted on the base frame. The base frame has a height that is sufficient to hold the marine platform sufficiently high above the sea surface in the respective sea depth once its support feet have been extended. The base frame is thus provided for erection of a self-erecting marine platform that is known per se to a person skilled in the art, for example from EP 0 959 182 B1. The self-erecting marine platform has hydraulically or pneumatically extendable support columns, with which the self-erecting marine platform is supported over the support regions of the foundation framework of the base frame. Once the support regions have been contacted, the base frame is connected rigidly to the support columns of the self-erecting marine platform.

In accordance with a preferred embodiment, the base frame has cable guide means, which are designed to guide underwater cables from the seabed to the marine platform. In accordance with this advantageous development of the invention, the marine platform, which for example has electrical components for transforming an electrical alternating or direct voltage, can be installed independently of the underwater cables, and thus on land, and the electrical properties and electric strengths of said marine platform can be tested. The marine platform thus completely finished and tested is then towed floatingly on the water to the base frame and is erected thereon. The electronic components can then be connected to the underwater cables, which have already been guided from the water. The underwater cables are already installed rigidly on the cable guide means. The erection of the marine platform is thus also simplified. The electric components of the self-erecting marine platform are, for example, transformers, converters, switchgears, filter means and the like, wherein the transformers are designed for transforming voltages of a few tens of kilovolts to a few hundred kV.

The cable guide means are expediently connected rigidly to the foundation framework. In a variant of the invention, the cable guide means are designed as an internally hollow cable guide tower.

The cable guide tower is expediently of such a height that, when installed, its free end protruding from the water is arranged at the height of a housing or pontoon of the finished, installed marine platform. In accordance with this advantageous development, the base frame is equipped on land with a cable guide tower. The base frame is then transported to its point of use, for example with the aid of a ship, and is anchored to the sea floor. The underwater cables are then guided through the cable guide tower as far as the free end thereof. Lastly, the self-erecting marine platform is fitted on the base frame and the electrical components of the marine platform are connected to the underwater cables.

In accordance with a preferred embodiment, the cable guide means are equipped with an interface, to which the free ends of the underwater cables are fastened. The cables of the marine platform can then likewise be connected to the interface.

The base frame is expediently equipped with locking means for anchoring the self-erecting marine platform. The locking means enable a rigid, sturdy connection between the marine platform and the base frame.

Further embodiments and advantages of the invention are presented by exemplary embodiments of the invention with reference to the figures of the drawing, wherein like reference signs denote functionally like components and in which:

FIG. 1 shows a schematic view of a first exemplary embodiment of the base frame according to the invention, and

FIG. 2 shows a schematic view of a further exemplary embodiment of the base frame according to the invention.

FIG. 1 shows an exemplary embodiment of the base frame 1 according to the invention, which is anchored rigidly to a sea floor 2.

To this end, the base frame 1 has locking means in the form of anchor feet 3, which are connected rigidly to a foundation framework 4. The foundation framework 4 is equipped with support regions 5 oriented parallel to the sea floor and on which bearing columns 6 of a self-erecting marine platform 7 are supported. Besides the bearing columns 6, the self-supporting marine platform 7 also has a housing or pontoon 8, in which components (not illustrated in the figures) of a transforming station for transforming a medium voltage into a high voltage are housed. The bearing columns 6 of the marine platform 7 are connected rigidly to the base frame 1 by connection means (not illustrated in the figures). The sea surface 9 and the sea depth T as well as the height H at which the pontoon 8 of the self-erecting marine platform 7 is held above the sea surface 9 are further illustrated schematically in FIG. 1. In the exemplary embodiment shown, the water depth T is approximately 80 meters.

With the aid of the base frame 1, it is even possible to use self-erecting marine platforms 7 at sea depths T that are greater than 45 m. To this end, the base frame 1 is first transported to the place at which the marine platform 7 is to be erected. The base frame 1 is first anchored rigidly to the sea floor 2 by the anchor means 3. The self-erecting marine platform 7 is then towed with its floating pontoon 8 to the base frame 1 and is positioned precisely over said base frame so that the bearing columns 6 are arranged directly above the support regions 5. The bearing columns 6 are then extended toward the base frame 1 via hydraulic means (not illustrated), until the floating pontoon 8 rises from the water and is held above the sea surface 9 at the height H of 13 m for example. The marine platform 7 is connected rigidly to the base frame 1 via connection means (not shown).

FIG. 2 shows a further exemplary embodiment of the base frame 1 according to the invention, which in this case is equipped with a cable guide tower 10, which extends out of the water from the sea floor 2 as far as the pontoon 8 of the self-erecting marine platform 7. The cable guide tower 10 is welded rigidly to the foundation framework 14 of the base frame 1 by connection means 11.

Underwater cables 12 are introduced into the cable guide tower 10 from beneath and extend as far as the upper free end of the cable guide tower 10, which is arranged at the height of the pontoon 8 of the marine platform 7. Once the marine platform 7 has been erected, the underwater cables from the cable guide tower 10 can be easily connected to the components of the marine platform 7. The marine platform 7 can thus be fabricated independently of the base frame 1, and electronic components of said marine platform, such as transformers, switches or the like, can be tested.

It can further be seen in FIG. 2 that the anchor means 3 are formed as foundation columns, of which the free end extends deep into the sea floor 2. Above the sea floor 2, each foundation column is part of the foundation framework 4.

The housing or floatable pontoon 8 of the marine platform 7 has a plurality of stories 13, in which the electrical components are housed. A hoisting crane 14 and a helipad 15 are located on the pontoon 8. 

1-11. (canceled)
 12. A base frame for a self-erecting marine platform, the base frame comprising: anchors configured to anchor the base frame to the seabed; and a foundation framework rigidly connected to said anchors, said foundation framework having support regions configured to support the marine platform.
 13. The base frame according to claim 12, which further comprises a cable guide configured to guide underwater cables from the sea floor to a pontoon of the marine platform.
 14. The base frame according to claim 13, wherein said cable guide is rigidly connected to said foundation framework.
 15. The base frame according to claim 13, wherein said cable guide is constructed as an internally hollow cable guide tower.
 16. The base frame according to claim 15, wherein said cable guide tower has a free end and a height causing said free end to protrude from the water at a height of a pontoon of the installed marine platform.
 17. The base frame according to claim 13, wherein said cable guide has an interface configured to be connected to the underwater cables and configured to connect cables of the marine platform.
 18. The base frame according to claim 12, which further comprises connectors configured to rigidly connect the base frame to the self-erecting marine platform.
 19. A method for erecting a marine platform, the method comprising the following steps: rigidly anchoring a base frame to the sea floor beneath the sea surface; supporting a self-erecting marine platform on the base frame; and then rigidly connecting the base frame to the self-erecting marine platform.
 20. The method according to claim 19, which further comprises: positioning the marine platform floatingly above the base frame; and then extending bearing columns of the floating marine platform downwards toward the base frame.
 21. The method according to claim 19, which further comprises, after the step of anchoring the base frame to the sea floor, guiding underwater cables from the sea floor through a cable guide fastened to the base frame and fastening the underwater cables to the cable guide.
 22. The method according to claim 21, which further comprises connecting components of the marine platform to the underwater cables. 